Friction clutch



W. S. WOLF RAM FRICTION CLUTCH Filed Feb.

` gf Y "/l (Ittornegs Aug. 1940.v

W le; 27

l 40 broken away and in section.

Patented Aug. 13, 1940 UNITED. STATES PATIENT OFFICE y mIC'rIoN CLUTCHl William S. Wolfram, Dayton, Ohio, assignor to General Motors Crporat'iom Detroit, Michga corporation of Delawa`re v Application February 27.1939, Serial No.l`258,645

2 claims. (C l mitted between the driven plate -and the hubv This inventionrelates to vfriction clutches and has been made as the result of an effort to imf prove the vfriction clutch through theinstrumentality of which the engine'of the motor ve- 5 hicle drives the transmission input shaft.`

nfclutches of the kind referred to there is usually provided a cover xedly secured to but having an abutment portion spaced from the ilywheel on the engine shaft. Adapted to be 1u gripped between the face of the ywheel'and an axially movable pressure plate is the driven plate. A suitable spring in vabutment with the cover plate biases the pressure plate to its active position. Means is also provided'to release the pres- .15 sure. plate from the action' of the -spring and usually yieldable means is'also provided to reciprocate the'y pressure plateaway from-the ily-l wheel when the clutch is to be released. The ypresent invention is of this kind and it includes an improvement inthe mounting of the clutch yengaging spring and ini-the vparts 'associated therewith. It also includes improvements in the mechanism by which the pressure plate is centered relative to and is made to rotate with the ywheel and by which the pressure plate is moved away from the lywheel'when the clutch` is disengaged.

I'he main object ofvv the invention is to improve and simplify a clutch in the above particulars 3|) and by the use of structure'whichshall be highly Numeral 'l represents the engine shaft and 9` the ywheel secured thereto as at II. To the flywheel is attached a cover I3 by circumferentially spaced fastening means I5, the coverbeing shaped as shown by Figure 1 to provide openings Il between the adjacent fastening means.

5o Within the cover is a pressure plate I9. Projecting into the closure formed bythe cover is a driven shaft 2|. It 'carries a hub 23 mounted to rotate with shaft 2|. A driven plate 25 with acin'gs 2l is associatedvwth the hub, there being 55 shown coil spring 29 by which torque is transwheel and' pressure plate. claimed for the structural details of vthese l. 19a-Lts)v l when the driven plate is gripped between'thefly- No novelty. is herein cushioning torque transmitting springs andfurther description o ftheir mounting need not' be given.

In accordance with the invention the spring I by which. the pressure plate is moved to grip the drivenplate is of the Belleville washer type. The `10 drawing shows Yit in the form of a'cone'd discy 3|. Along its circular outer edge 33 the spring engages the pressure plate. Radially inward from its!` line contact at 33 itis in abutment with a circular.;

bulged formation 35pm-.the cover. The annulus 1 5 Ybetween-the circles at 33 and 35 is unbrokeneand ythe spring, inl-being assembled, is so prestressed from its more conical unloaded formas'to exert f axial pressure on the pressure plate the cover serving as .the abutment.` Slots 3'I extendl from 20 the circular inner margin 39 of thespring to apertures 4| so shaped as'to minimize splitting of the material adjacent the periphery. v In prior practice such a spring has been supported by a plurality of-pins carried by the cover 25 and extending/through the equivalent 'of'openings -4|. Rings have been supported on these vpins toy serve as 'circular contact members orA ful-cra for-the spring. My presentiarrangement is ofjmuch' simpler form..V` I use" an: annular 30 member 43. This member has axially extending iingers 45 which pass through apertures 4| and the endsof these ngers are welded to the coverat 41. Within the coverV and spring 3| the annulus 43 is'bent to form an acute angle at 49 and 35 is shaped at its margin to form a rounded spring abutment 5|. rThis abutment 5| ylies closely ad'- yjacent to .but Vis spaced from the abutment 35';

sufficiently to `accommodate the spring as shown in Figure l. 'This inexpensive single part 43 thus 4U centers the spring andserves as a fulcrum bearing taking the place .of thepins and rings heretofore used.

The invention also makesuse of novel andin.`

expensive means whereby the pressure plate is 45 'i centered and -made to rotate with the iiywheel 'without the provision'of notches and driving.'

lugs. A plurality of metal springs 53 are bent from flat spring steell into U-shape as shown by Figure 4. -Thesidesfat tneir ends are secured at 55 and 5l to the pressure plate and cover.

Through the instrumentality of\ these springs of which there may be four, distributed symmetrically, the rotation of the cover is transmitted to the pressure plate. Also when the 5 5 main spring 3l pushes the pressure plate to clutch engaging position, each spring 53 is stressed. When the clutch is released these springs 53 insure axial reciprocation of the pressure plate to full releasing position. The springs 53 therefore serve to transmit the drive from the iiywheel to the pressure plate, to insure the releasing movement of the pressure plate, and they serve to center the pressure plate in the assembly.

The action of the Belleville spring in effecting the clutch engagement will be appreciated without further description. To release the clutch, pressure is applied by any convenient form of clutch releasing lever, not shown, to the ring 51. This pressure takes the load of the spring from the line contact at 35. The spring then moves about 5I as a fulcrum and the spring load is removed from the pressure plate. Spring 53 which was put in tension by the action of the main spring in effecting clutch engagement now serves to withdraw the pressure plate away from the flywheel.

I claim:

1. In a clutch. a flywheel, a cover having a central opening. a pressure plate within said cover, a

driven plate adapted to be gripped between said .flywheel and pressure plate, a conical spring in peripheral engagement with said pressure plate and having a circular Line contact with said cover, an annular member having parts extending axially within the cover opening and secured to said cover and having a circular fulcrum line adjacent to but spaced axially from said cover contact line, and means to relieve the pressure of said spring from said rst line contact and to use said second line Contact as a ulcrum to effect clutch release.

2. In a clutch, a flywheel, a cover having regions spaced axially from the flywheel, a pressure plate within said cover, a driven plate adapted to be gripped between said flywheel and pressure plate, main spring means engaging said pressure plate and in abutment with said cover, U- shaped flat springs having legs attached to the pressure plate and cover, the attachment to the cover being to the said spaced regions thereof, said fiat spring centering the pressure plate transmitting torque thereto` and serving to move the pressure plate to its clutch releasing position.

WILLIAM s. WOLFRAM. 

